Ten of us - a motley crew made up of the young South African hip hoppers Prophets of Da City and their PR, the photographer and me - are wandering down Wornington Road near Portobello market when we chance upon a white-shirted policewoman. Obviously intrigued, she enquires about our destination. After I've explained that we're looking for a photo location, she says, in a concerned voice: "You know this is not a very nice area. Golborne Road is one of the main drug-dealing places around here."

I couldn't help laughing at the paradox. Here were seven young so-called "coloured" (they spit it out with venom) South Africans, who were brought up in the townships and have experienced first-hand the fearful violence, drugs and gangs that is and was South Africa, being warned about the dire perils of west London's dear old Golborne Road. Meanwhile, the boys themselves are more interested in posing hip hop style against walls of colourful London graffiti.

On stage, Prophets of Da City rap, breakdance, scratch vinyl - sometimes with a nose or a foot - act crazy in a funny way, sing strident political lyrics and generate huge amounts of energy. In fact, going to a Prophets of Da City gig is like visiting their township, Mitchell's Plain near Cape Town. They emanate that feisty street vibe on and off the stage.

Together for 11 years, Prophets of Da City started out as a breakdancing crew and progressed into one of South Africa's most visible rap groups. "POC is one of the most recognised bands in South Africa," says 26-year- old DJ and breakdancer Ready D, one of the Prophets' founder members. "But we're not respected and supported financially as we should be. We are thought of as too radical or as just a bunch of kids."

Yet POC was the only band privileged to play at Mandela's inauguration ceremony in Pretoria last year. So what do they think of President Mandela? "We have a lot of respect for him," says Ready D. "He was locked up for 27 years and he came out in peace and with respect for the enemy. He has our full support."

Recently interviewed by The Face, Ready D is concerned that the journalist made so much of the "coloured" (mixed-race South Africans, many of Malaysian origin) issue. "I don't see myself as coloured, number one," says shaven- headed Ready D, "and there is still no respect in South Africa for the so-called coloured population. Calling someone coloured is a total form of disrespect whether it comes from a black or a white man." As a boy, Ready D had to go through the indignity of the pencil test. "They tried to stand a pen in your hair and if it fell then you were classified as European and if it stuck you were coloured."

Ready D was brought up initially in Cape Town's District Six, but in 1979 the government announced that everyone had to leave this valuable piece of real estate for the Mitchell's Plain township. So Ready D and his family were forcibly resettled in the barren Cape Flats. By the age of eight, Ready D was already in trouble for house-breaking and theft. "My worst crime at that age was breaking into a school," he says. "We didn't give a damn. But I do remember the beating my father gave me."

But at 11 he was breakdancing for money following the death of his father. "I was out there dancing just to put bread on the table," he says. "Then later I started to practise with the turntable, day in, day out. At the weekends, we'd take the hi-fi out into the road and dance. Then, later on, I'd have 20 to 30 people in our little home and neighbours would start banging on the walls. My mother found it nerve-racking."

Riots in 1985 - when tanks roamed the streets - politicised both Ready D and another founding member of POC, the hyperactive Shaheen. "It was the first time that blacks and so-called coloureds came together and said, 'We're fighting,' " says Ready D. "I was throwing bricks and petrol bombs at whites, not knowing why I was doing it. I just wanted a piece of the action. We were brought up in hate. It's a mentality that still exists."

Shaheen was also involved in student action at school. "There was one time when an election for so-called coloured representatives was going on, but it was a complete con," he recalls. "We burnt tyres so people wouldn't be able to vote. The police drove around shooting at us from normal cars so we didn't realise it was them. When we saw the bullets coming it was like the Gulf War. We jumped over walls that I know I couldn't get over now. Kids used to live on the top of flat-roofed flats and let you know by coded whistles where the police were."

These days, however, Prophets of Da City have a proactive anti-violence and anti-drugs message which they often express through their music and improvised plays in townships, schools and prisons. "We took notice of bands like Public Enemy which were saying things like, 'Be proud to be yourself and stop killing one another,' " says Ready D.

Although their mothers regarded hip hop as "the swearing music", Prophets of Da City started to record tracks like "Fuck the Government" on a small eight-track recording studio owned by Shaheen's father. They were very popular with their peer group. "We became the voice for the community," says Ready D. "We still get people saying they've just found one of those tapes."

Later records retained that hard edge. In fact, their second album, The Age of Truth, was banned by the SABC for having lyrics like "the Minister of Justice is a sick fuck" and "FW De Clerk is an asshole". "It was the first time that a record in South Africa took such an approach," says Ready D, "but we also denounce black people if they are selling out their communities."

Prophets of Da City are hardly young innocents abroad - Ready D and Shaheen were involved in street violence, while dancer Jazzmo was a gang member and breakdancer Ramone sniffed petrol and smoked Mandrax. They believe that forming the band created their escape route. They are very conscious of their own choice. "All my friends were in gangs," says Ready D. "A lot of them are in prison for murder. Everyone expected me to go down that route. I can remember when people were being stabbed to death for their Ray Bans."

Prophets of Da City have set up the African Hip Hop Alliance Support network. "It's something positive for kids to join," explains Shaheen, "and it was our way out. We want to help kids get into the music industry."

These days, Prophets of Da City's families are supportive of their music. "And they're still supporting us financially," laughs Shaheen. "We're always doing everything for nothing." The band are in England as part of their attempt to break into the lucrative international market, but confess that they are homesick. "Portobello Road is just too English," says Shaheen. "We'd prefer to be in Brixton, somewhere that's a bit more like home."

After all, Brixton Academy's the place where they supported James Brown. "Our friends at home just didn't believe it, so we took photographs to prove it," says Shaheen proudly. "Not that we believe in that sort of hero-worship shit."

n Prophets of Da City's new single "Wild Stylez" was released this week. Their album 'Universal Sluggish' follows on 21 Aug